Characterization and fine mapping of a new early leaf senescence mutant es3(t) in rice

Abstract

Leaf senescence is an important biological process during leaf growth and development. In this study, we isolated a novel rice mutant, early senescence 3 (es3(t)), from the offspring of the wild-type rice cultivar Wuyunjing 7 after ethyl methanesulfonate mutagenesis. The es3(t) exhibited yellowing leaves, decreased chlorophyll (a and b) and carotenoid contents during the growth period, and abnormal chloroplast structure. Early leaf senescence was accompanied with decreased photosynthesis. The content of abscisic acid was increased in es3(t) mutant, which indicates that abscisic acid probably plays an important role in leaf senescence. The expression levels of senescence-associated transcription factors and senescence-associated genes were increased in the es3(t) plant, and the reactive oxygen species were accumulated in the senescence leaves of es3(t) plants. Genetic analysis demonstrated that early leaf senescence phenotype was controlled by a single recessive nuclear gene. Map-based cloning showed that ES3(t) was located on chromosome 3 with a 35-kb physical interval in the BAC AC097624 which included eight putative open reading frames. Based on these findings, we have identified a novel leaf senescence mutant which is a useful resource for revealing the molecular mechanism of early leaf senescence in rice.